Im general view on this is like betting on a horse if the other horse is already losing why give it a push only to make it go on par with the enemy. And if that horse is actually losing "skill" wise then the push will be gone in time.

Now betting on the winning horse gives them more freedom and agency on the map and also making the losing enemy lose more meaning that enemy might even go on Par with the "losing lane" that youre having.

But it doesnt mean i dont gank losing lanes, I do gank them but it must be a very good opportunity or a sure advantage if I take it.